<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
    <style>
        .content{
            color: red;
        }
        .size{
            font-size: 40px;
        }

    </style>
</head>
<body>
    <p>大家好</p>
    <p>我很好</p>
    <p class="content size">我emo！</p>
    <p class="content" class="size">我没有没有</p>
</body>
</html>